In hospitals, clinics, and other health care facilities, a wide variety of medications are administered to the patients; many of these medications are administered orally. Oral administration generally requires that a dose of medication be deposited in a vial or other small container in the pharmacy of the health care facility, from which it is transported to the patient and ultimately administered. This procedure provides many opportunities for contamination or spillage, particularly because efficient operation of the pharmacy makes it desirable to pre-fill a number of vials of a given medication at one time, though use may be spread out over an entire day or even several days. If the vials are sealed at the time of filling, the patient or the nurse may experience difficulty in opening a vial at the time of administration, depending upon the type and construction of seal employed. Contamination at the time of filling is also a persistent problem.
A number of different constructions for sealed vials, primarily intended for multi-dose use as in the filling of syringes, are known in the art. One example of a closure construction for a multi-dose vial or the like is shown in Gould U.S. Pat. No. 3,013,687, issued Dec. 19, 1961. The Gould closure provides an elastomer stopper that is held in place by an apertured metal retaining ring which is in turn covered by a metal cap, with both the metal retaining ring and the cap being crimped over the lip of the vial. The outer cap is readily removed by means of a release tab, allowing the withdrawal of individual doses from the vial by a needle that punctures the elastomer stopper.
Another previously known closure structure for a multi-dose vial or like container is shown in Hershberg et al U.S. Pat. No. 3,424,329, issued Jan. 28, 1969. That closure construction employs a resin disc and a superimposed elastomer disc closing off the opening to the vial; a resin sealing ring engages the periphery of the elastomer disc and extends downwardly to encompass the lip of the vial, with the entire closure assembly being held in place by a metal sealing ring crimped to the vial and having a central opening allowing access to the elastomer disc. In use, the contents of the vial are removed, in individual doses, by inserting a needle through the two closure discs and into the interior of the vial.
Another construction for a multi-dose sealed vial, which minimizes the possibility of contamination due to puncturing of the elastomer seal member, is shown in Zackheim U.S. Pat. No. 3,823,840 issued July 16, 1974. This closure employs an elastomer disc covering the neck of the vial and in turn covered by a metal film; a metal cap crimped to the neck of the vial covers the metal film and holds the assembly together. The central portion of the cap incorporates a tear tab that can be removed, followed by removal of the metal film to expose a semi-circular slit valve in the elastomer closure member through which individual doses of medication can be withdrawn.
Unit dose disposable syringes are also known in the art, an excellent example being Baldwin U.S. Pat. No. 3,729,031 issued Apr. 24, 1973. That device employs an elastomer plunger having a slit valve that permits filling of the syringe from the rear, the plunger valve re-sealing itself for future use in discharging medication from the syringe.
For a vial intended for oral administration of medication, the closure should permit filling the vial while in clean and sterile condition without removing or altering any part of the closure and without requiring puncturing of any closure element. At the same time, the closure assembly for a unit dose vial for oral administration should permit rapid and convenient removal of the entire closure by either a nurse or a patient at the time of administration. In addition, the closure assembly ought to be simple and inexpensive and should maintain sterile conditions at all times. These sometimes conflicting requirements are not effectively met in the prior art devices.